{ INFORMATICS.MCCME.RU
  Problem statement: http://informatics.mccme.ru/moodle/mod/statements/view3.php?chapterid=3
  Verdict: Accepted
}
uses SysUtils;
 
var
	n,k,ans:longint;
 
begin
reset(input,'input.txt');
rewrite(output,'output.txt');
read(n);
k:=1;
ans:=0;
while k<n do begin
	k:=k shl 1;
	inc(ans);
end;
write(ans);
end.